Sort the first n elements of [ first ... last ) where n = min (( last - first ), ( result_last - result_first )) and place the result into [ result_first...result_first + n ). Return the smaller of result_last or result_first + n , where n = last

first . The first version sorts the elements using operator< , whereas the second version uses the binary function compare .

Declaration


  
#include <algorithm>

template< class InputIterator, class RandomAccessIterator >
RandomAccessIterator partial_sort_copy
  (
  InputIterator first,
  InputIterator last,
  RandomAccessIterator result_first,
  RandomAccessIterator result_last
  );

template
  <
  class InputIterator,
  class RandomAccessIterator,
  class Compare
  >
RandomAccessIterator partial_sort_copy
  (
  InputIterator first,
  InputIterator last,
  RandomAccessIterator result_first,
  RandomAccessIterator result_last,
  Compare compare
  );

Complexity

Time complexity is ( last - first )* log ( n ). Space complexity is constant.

Example <ospace/osstd/examples/parsrtc0.cpp>


    #include <iostream>
#include <algorithm>
#include <iterator>
#include <vector>

int numbers[ 6 ] = { 5, 2, 4, 3, 1, 6 };

void
main()
  {
  int result[ 3 ];

  partial_sort_copy
    (
    numbers,
    numbers + 6,
    result,
    result + 3
    );

  for ( int i = 0; i < 3; ++i )
    cout << result[ i ] << ` `;
  cout << "\n";
  }

1 2 3

Example <ospace/osstd/examples/parsrtc1.cpp>


    #include <iostream>
#include <stdlib.h>
#include <algorithm>
#include <iterator>
#include <vector>

void
main()
  {
  vector< int > v1( 10 );
  for ( int i = 0; i < v1.size(); ++i )
    v1[ i ] = rand() % 10;
  vector< int > result ( 5 );
  ostream_iterator< int > iter( cout, " " );
  copy( v1.begin(), v1.end(), iter );
  cout << "\n";

  partial_sort_copy( v1.begin(), v1.end(), result.begin(), result.end() );

  copy( result.begin(), result.end(), iter );
  cout << "\n";
  }

6 0 2 0 6 7 5 5 8 6
0 0 2 5 5

Example <ospace/osstd/examples/parsrtc2.cpp>


    #include <iostream>
#include <string.h>
#include <algorithm>
#include <iterator>
#include <vector>

char* names[] = { "aa", "ff", "dd", "ee", "cc", "bb" };

bool
str_compare( const char* a_, const char* b_ )
  {
  return ::strcmp( a_, b_ ) < 0 ? 1 : 0;
  }

void
main()
  {
  const unsigned nameSize = sizeof( names ) / sizeof( names[ 0 ] );
  vector< char* > v1( nameSize );
  for ( int i = 0; i < v1.size(); ++i )
    v1[ i ] = names[ i ];
  ostream_iterator< char* > iter( cout, " " );
  copy( v1.begin(), v1.end(), iter );
  cout << "\n";
  vector< char* > result ( 5 );

  partial_sort_copy
    (
    v1.begin(),
    v1.end(),
    result.begin(),
    result.end(),
    str_compare
    );

  copy( v1.begin(), v1.end(), iter );
  cout << "\n";
  }

aa ff dd ee cc bb
aa ff dd ee cc bb

partial_sort_copy

Library

Declaration

Complexity

Example <ospace/osstd/examples/parsrtc0.cpp>

Example <ospace/osstd/examples/parsrtc1.cpp>

Example <ospace/osstd/examples/parsrtc2.cpp>